In hearing aids the sound produced is to be delivered to the ear of the wearer of the hearing aid. Thereto a hollow tube is provided for delivering the acoustic signal to that part of the hearing aid which is located in the ear. This requires a tube of a certain diameter that is clearly visible to other people. In RIC hearing aids electrical signals are delivered from a behind-the-ear (BTE) part to the Receiver-in-canal (RIC) part of the hearing aid. This allows for a much smaller tube containing the wires for conducting the signals. The trend is to make the diameter of these tubes as small as possible, but the problem then is that the strength of the tubing is also reduced, and as a consequence robustness is not sufficient anymore. To address this Estron has developed a method for providing an extruded cable “Eslinum” that allows extruding the insulation material tight around the wires, while facilitating stripping of the insulation without damaging the wires. The tensile strength is improved by improved by applying Aramide fibers. This is results in a strong cable with a small diameter, which in contrast to a tube, is not hollow. Though this pre-vents acoustical feedback and entering of sweat, moisture or ear wax to the inside of the cable, it does not prevent the wires from experiencing stress or tension when pulling or bending forces are exerted on the cable; e.g. when the cable is pulled at one end. In U.S. Patent Application Publication No. 2011/0094718, this is addressed by providing a hollow tube carrying a conductor wherein the conductor has a length exceeding that of the tube. The conductor carries one or more electrical wires and is spirally preformed. As the tube is hollow, the conductor is free to move and does not experience stress or tension when pulling or bending forces are exerted upon the tube. However, this puts a limit on the minimal diameter of the tube and requires preforming of the conductor.
It is an object of one or more embodiments of the present invention to provide a method for producing a tube for a hearing aid in that alleviates the above drawbacks.